Barbour. 

Mammalian  fossils  from  Devil's 
Gulch  ( Nebraska, 


33 


NEBRASKA 
GEOLOGICAL  SURVEY 

ERWIN  HINCKLEY  BARBOUR,  State  Geologist 
VOLUME  4 

PART     1 

MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH 


BY 

ERWIN  H.  BARBOUR 


GEOLOGICAL  COLLECTIONS  OF  HON.  CHARLES  H.  MORRILL 
REPRINT  FROM  THE  UNIVERSITY  STUDIES 


191   B 


ITY  o^  CAT  ^^ 

S.-  NTA   EAKBAEA 


MAMMALIAN   FOSSILS   FROM  DEVIL'S   GULCH 

BY   ERWIN    H.    BARBOUR 

The  fauna  of  the  beds  at  Devil's  Gulch  and  vicinity  is  rich  and 
varied,  and  promises  to  fill  certain  gaps  in  the  Pliocene  and  early 
Pleistocene,  where  investigation  seems  especially  desirable.  The 
object  of  this  paper  is  to  make  a  partial  faunal  list  and  to  de- 
scribe two  new  proboscideans. 

ANCESTRAL  PROBOSCIDEANS 

The  genealogy  of  this  group  is  now  so  well  known  to  natural- 
ists, that  it  is  interesting  to  note  in  the  writings  of  Cope  and  others 
of  twenty-five  years  ago,  that  the  intermediate  proboscideans  are 
entirely  lost,  and  the  phylogeny  of  the  order  absolutely  unknown. 
As  a  reward  of  zeal,  the  genetic  gaps  are  being  filled  so  rapidly, 
that  ultimately  knowledge  of  the  history  of  the  Proboscidea  must 
be  as  well  known  as  that  of  the  Equidae.  The  affinities  of  the 
Proboscidea  are  with  the  Rodentia  and  Sirenia. 

The  oldest  known  progenitors  of  the  Proboscidea  are  Moeri- 
therium  and  Palaeomastodon.  Moeritherhim  occurs  in  the  Upper 
Eocene,  and  Palaeomastodon  in  the  Lower  Oligocene  of  Egypt,  so 
Africa  is  accounted  the  birthplace  of  the  group.  After  centuries 
of  change  their  migrations  took  them  throughout  Africa,  north- 
ward into  Europe  and  the  British  Isles,  into  Euro-Asia,  India,  and 
Siberia,  thence  across  the  Siberian-Alaskan  Isthmus  of  that  time 
into  North  America,  and  by  the  Isthmus  of  Panama  into  South 
America.  Thus  they  became  world-wide  in  distribution. 

During  the  ages  required  for  these  mutations  and  migrations, 
many  degrees  of  specialization  resulted. 

THE   SKULL 

While  the  trunk  and  tusks  were  developing  until  they  became 
ponderous,  the  superficial  area  of  the  skull  was  also  increasing. 


178         NEBRASKA  GEOLOGICAL  SURVEY 

Otherwise  there  would  not  have  been  the  extent  of  surface  neces- 
sary for  the  attachment  of  muscles  and  ligaments  to  carry  the 
ever-increasing  load.  This  expanse  of  surface  was  brought  about 
by  the  inflation  of  air  cells  in  the  cant  ellous  tissue.  This  structure 
not  only  surrounds  the  brain,  but  extends  into  the  maxillae,  zygo- 
matic  arch,  and  other  parts  of  the  skull. 

At  first  the  proboscis  was  small,  but  little  more  than  a  pre- 
hensile lip,  much  like  that  of  the  horse,  and  used  in  much  the 
same  way,  to  guide  food  into  the  mouth.  In  the  later  mastodons, 
mammoths,  and  modern  elephants,  perfection  of  specialization 
was  attained  by  this  remarkable  organ.  This  too  added  to  the 
weight  of  the  skull. 

THE  MANDIBLE 

The  lengthening  and  subsequent  shortening  of  the  mandibular 
tusks  was  paralleled  by  the  lengthening  and  subsequent  shortening 
of  the  mandible  itself.  The  remotest  known  ancestor  of  the  group 
had  mandibles  of  a  typical  mammalian  form,  which  in  successors 
became  increasingly  atypical.  As  the  mandibular  tusks  developed, 
mastodons  became  longirostral  to  the  last  degree.  The  symphysial 
prolongation,  which  was  extreme  in  Mastodon  angustidens,  is  re- 
duced in  the  mammoths  and  present  elephants  to  a  mere  process 
on  the  front  of  the  jaw. 

THE  TEETH 

The  ancestral  proboscidean  had  a  number  of  teeth,  after  the 
manner  of  typical  mammals,  and  these  were  erupted  in  the  usual 
way,  that  is  by  new  teeth  pushing  upward  and  gradually  displacing 
the  old.  These  are  called  teeth  of  vertical  succession.  But  inci- 
dent to  progressive  change,  and  extreme  specialization,  the  teeth 
of  mastodons  and  mammoths  became  too  large  for  the  jaw  to 
accommodate  many  at  a  time,  and  finally  the  dentition  was  reduced, 
in  fully  matured  adults,  to  one  large  specialized  tooth  in  each 
jaw.  These  teeth  were  erupted  in  a  singular  manner,  that  is,  by 
the  one  behind  crowding  forward,  and  pushing  out  the  one  in 
front.  This  is  known  as  the  horizontal  succession  of  teeth.  Ac- 


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MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  179 

cordingly,  the  anterior  cones  and  plates  of  mastodons  and  mam- 
moths are  ground  in  front  long  before  they  are  worn  behind. 

The  mandibular  teeth  of  mastodons  are  ground  most  in  front, 
and  generally  with  an  outward  slant.  This  gives  a  clue  to  the 
orientation  of  odd  mastodon  teeth.  The  mandibular  teeth  of 
mammoths  are  roughly  crescentic,  the  ground  or  worn  surfaces 
are  upward  and  forward,  and  the  convexity  inward,  which  enables 
one  to  orient  and  locate  a  given  tooth.  The  maxillary  teeth  of 
mammoths  are  generally  massive,  the  grinding  surface  is  down- 
ward, and  the  greater  convexity  of  surface  outward. 

Though  the  more  advanced  and  specialized  proboscideans  have 
the  number  of  grinding  teeth  reduced  to  one  or  two,  they  may  have 
had,  at  some  earlier  stage  in  their  life,  four  or  five  in  use  at  once. 
This  points  to  an  ancestry  with  many  grinders.  The  short- 
crowned  (brachydont)  teeth,  with  but  three,  four,  or  five  trans- 
verse ridges,  changed  to  the  tall-crowned  (hypsodont)  teeth  with 
ever-increasing  transverse  ridges  found  among  the  intermediate 
and  true  elephants.  Increase  in  number  of  ridges  signifies  ad- 
vancement. The  earlier  mastodons  had  3  transverse  ridges,  later 
mastodons  4  or  5.  The  intermediate  elephants,  Stegodonts,  had  6 
to  12,  and  the  mammoths  and  modern  elephants  16  to  24,  and  even 
28.  Along  with  the  multiplication  of  transverse  ridges  went  the 
increase  in  cement  reinforcement  signifying  specialization. 

THE  TUSKS 

Morphologically,  tusks  are  incisors  which  grow  from  persistent 
pulps.  A  series  of  fossil  proboscideans  show  that  the  tusks  gradu- 
ally lengthened,  and  increased  in  weight,  during  the  ages,  until 
they  became  ponderous.  Great  muscles  and  sinews  were  neces- 
sary to  support  the  weight  of  the  ever-lengthening  tusks  and  trunk. 
Accordingly,  insensible  changes  took  place.  The  early  dolico- 
cephalic  skull,  and  longirostral  jaw  changed  to  the  brachycephalic 
and  brevirostral. 

Early  mastodons  had  short  decurved  tusks  with  enamel  bands. 
Intermediate  mastodons  had  longer  and  larger  tusks  with  vestigial 
enamel  bands,  while  later  ones  had  long,  straight,  or  slightly  spiral 
tusks  with  the  enamel  band  wanting.  Though  mastodon  tusks  are 


180         NEBRASKA  GEOLOGICAL  SURVEY 

generally  slim  and  relatively  straight,  there  are  many  examples 
with  large  dimensions  and  extreme  curvature.  The  persistence  of 
this  vestigial  enamel  band  even  in  modern  elephants  is  significant. 
A  foot  or  so  may  still  be  seen  on  young  elephant  tusks.  This  is 
soon  worn  off  by  use.  Mammoths  generally,  though  not  invari- 
ably, have  ponderous  tusks  distinctly  curved  and  spiral.  Those 
found  in  this  State  are  noticeably  spiral. 

MASTODONS  IN  GENERAL 

Cope's  classification  of  the  mastodons  has  for  a  long  time  made 
the  strongest  popular  appeal.  He  divided  them  into  Tetrabelodon, 
or  the  four-tuskers,  and  Dibelodon,  or  the  two-tuskers.  This 
simple  division  gives  the  public  a  clue  to  the  primary  divisions 
of  the  group.  These  terms  are  particularly  appropriate  and 
descriptive. 

Mastodons  may,  in  a  similar  manner,  be  classed  according  to 
the  lobes  of  their  teeth,  as  Trilophodonts  (three-crested  molars) 
and  Tetralophodonts  (four-crested  molars).  Though  serving  the 
purposes  of  the  naturalist,  this  latter  division  is  less  obvious  than 
the  former.  Both  of  these  general  classifications  are  very  useful. 

ELEPHAS 
(Modern  Elephants) 

•True  Elephants 
MAMMOTHS 
(Intermediate  Elephants) 

STEGODONS 
(Intermediate  Mammoths) 

MASTODONS  }  True  Mastodons 

(Advanced  type) 

\  DIBELODON 

\  (Two-tuskers) 


TETRABELODON 
(Four-tuskers) 

DlNOTHERIUM.  / 

\  PALAEOMASTODON 

\  / 

MOERITHERIUM 

ANCESTRAL 
PROBOSCIDEAN 


Ancient  Mastodons 


NEBRASKA  GEOLOGICAL   SURVEY 


VOLUME  4,  PART   II,  PLATE  4 

7,  Mammoth. 

Pleistocene. 

Three  species,  the  Colum- 
bian, Imperial,  and  Primi- 
tive are  abundant  in  Ne- 
braska. 


6,    Mastodon. 
Mastodon  americanus. 
Common  in  Nebraska. 
Pleistocene. 


5,  Eubelodon  morrilli. 

An  early  mastodon. 

Pliocene. 

Devil's  Gulch,  Nebraska. 


4,  Tetrabelodon  willistoni. 
A  late  four-tusker. 
A  trilophodont  mastodon. 
Pliocene  of  Nebraska. 


3,  Tetrabelodon. 
An       early       four-tusked 
mastodon. 
Miocene. 


2,  Palaeomastodon. 
Lower  Oligocene,  Egypt. 


i,  Moeritherium. 
Ancestral  proboscidean. 
Upper  Eocene,  Egypt. 


PLATE  I 

Evolution  of  the  Proboscidea.  Freehand  sketches,  approximately  to 
scale,  from  casts  and  specimens  in  the  collection  of  Honorable  Charles  H. 
Morrill,  State  Museum. 


MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  181 

The  word  mastodon  has  gone  beyond  the  limits  of  scientific 
literature,  and  is  now  incorporated  in  our  common  speech.  It 
seems  to  be  the  best  and  most  expressive  single  word,  and  yet  the 
name  Gomphotherium  (wedge-toothed  beast)  was  proposed  first, 
and  has  the  right  of  priority.  The  reader  will  occasionally  find 
Mammut  in  use  by  some  writers,  as  Mammut  americanum,  which 
is  synonymous  with  Mastodon  americanus.  Our  word  mam- 
moth is  an  early  English  corruption  for  Mammut.  The  genus 
Mastodon  must  inevitably  undergo  many  subdivisions,  even  though 
the  multiplication  of  names  is  confounding  to  the  general  palae- 
ontological  reader. 

MASTODONS   AND   MAMMOTHS   IN    NEBRASKA 

Mastodons  in  Nebraska  date  from  the  late  Miocene,  continued 
through  the  Pliocene  and  Pleistocene  and  became  extinct  at  the 
close  of  the  glacial  epoch.  They  ranged  through  the  United  States, 
Canada,  Alaska,  and  Mexico.  The  present  collections  in  the  State 
Museum  show  at  least  seven  distinct  forms,  namely:  Mastodon 
zvillistoni,  M.  morilli,  M.  euhypodon,  M.  undetermined,  M.  unde- 
termined, M.  mercificus,  M.  americanus.  It  is  believed  that  masto- 
dons, though  earlier  arrivals,  outlived  the  mammoths. 

Three  species  of  mammoths  are  well  known  in  Nebraska, 
namely :  Elephas  imp  er  at  or,  E.  columbi,  and  E.  primigenius.  The 
most  majestic  of  them  all,  Elephas  imperator,  the  giant  imperial 
elephant,  with  a  height  exceeding  13  feet,  ranged  from  Nebraska 
westward  to  the  Pacific,  and  southward  to  Mexico,  during  Pleisto- 
cene times.  The  next  largest,  Elephas  columbi,  the  great  Co- 
lumbian elephant,  with  a  height  of  10  to  n  feet,  followed  in  the 
middle  Pleistocene,  and  ranged  over  the  entire  United  States  and 
Mexico.  These  two  mammoths  had  a  southern  adaptation.  They 
were  followed  by  a  mammoth  of  a  northern  adaptation  known  as 
the  great  northern,  or  hairy  mammoth,  Elephas  primigenius,  which 
had  a  height  of  9  feet.  This  is  the  mammoth  best  known  to 
the  public.  Its  range  was  west,  extending  from  the  Atlantic  to 
the  Pacific,  along  the  northern  part  of  the  United  States,  through- 
out British  Columbia,  and  over  Alaska.  Proboscideans  attained 
ponderous  size  at  a  surprisingly  early  period,  especially  in  Europe. 


182         NEBRASKA  GEOLOGICAL  SURVEY 


THE  DEVIL  S  GULCH  BEDS 

On  a  recent  collecting  trip  to  Devil's  Gulch  and  vicinity,  in 
northern  Brown  County,  a  large  and  varied  collection  representing 
the  mammalian  fauna  of  the  Loup  Fork  beds  of  that  region  was 
secured  for  the  University  Museum.  These  fossils  are  a  part  of 
the  extensive  palaeontological  collections  of  Honorable  Charles  H. 
Morrill,  and  may  be  counted  the  largest  and  most  important,  which 
have  ever  been  secured  for  the  University  in  so  short  a  time.  All 
of  the  material  is  highly  interesting  from  the  view  point  of  the 
palaeontologist,  and  some  of  it  is  new  and  of  first  importance. 

Early  in  May,  1913,  Mr.  A.  C.  Whitford,  an  assistant  on  the 
Nebraska  State  Geological  Survey,  and  a  Fellow  in  the  Depart- 
ment of  Geology,  was  sent  to  Devil's  Gulch  to  prospect  for  the 
bones  of  "  Tetrabelodon."  His  success  led  the  writer,  accompa- 
nied by  Mr.  Harold  Eaton,  to  join  him  at  once.  The  party  camped 
for  ten  days  in  Devil's  Gulch  and  obtained  two  wagon  loads  of 
excellent  material.  Exploratory  work  was  then  continued  by  Mr. 
Whitford  until  October. 

The  Niobrara  River,  which  is  the  boundary  between  Brown  and 
Keya  Paha  counties,  has  a  broad  valley,  perhaps  a  mile  across  at 
this  point.  The  land  immediately  adjacent  is  considerably  cut  by 
side  streams,  some  of  which  show  bold  bluffs  and  canyon  walls. 
Dutch  Creek  flows  for  several  miles  between  deep,  precipitous 
walls,  and  empties  to  the  north  into  the  Niobrara.  Extending  in  a 
northwesterly  direction,  as  a  tributary  to  Dutch  Creek,  is  Devil's 
Gulch,  a  narrow,  precipitous,  picturesque  canyon,  about  225  feet 
deep,  and  scarcely  more  than  a  mile  in  length.  Certain  portions 
of  the  canyon  are  heavily  forested  with  bull  pine,  yet  the  walls  are 
mostly  bare  and  precipitous  for  they  are  subjected  to  the  heavy 
erosive  action  of  wind  and  rain,  and  many  well-preserved  bones 
are  exposed.  This  Gulch  is  about  15  miles  north  of  Ainsworth, 
upon  the  three-thousand-acre  ranch  of  Mr.  William  A.  Jamison, 
through  whose  courtesy  the  University  was  allowed  to  collect  at 
will. 

A  geologic  section  of  the  place  is  readily  obtained  by  follow- 
ing the  course  of  the  canyon.  At  the  junction  of  the  Gulch  with 


NEBRASKA   GEOLOGICAL   SURVEY 


VOLUME  4,   PART   II.   PLATE  6 


Tetrabelodon  willistoni.  a,  top  view  of  skull  showing  a  narrow,  but 
well-arched  dome,  flattish  occiput,  expanded  anterior  nares,  and  greatly 
reduced  nasals.  Tool  marks  indicate  restored  parts,  b,  palatine  view, 
showing  bifurcated  maxillae,  narrow  posterior  nares,  and  teeth,  Nos.  I, 
2,  3,  and  4.  Tool  marks  at  base  of  skull  indicate  restoration. 


NEBRASKA   GEOLOGICAL   SURVEY 


VOLUME  4,   PART   II,   PLATE  7 


Skull   of   Modern   Elephant.     Top  and   side  views  of  Elephas  indicus. 
For  comparison  with   Tetrabelodon  willistoni.     From  a   specimen 
State  Museum. 


NEBRASKA    GEOLOGICAL    SURVEY 


VOLUME  4,   PART   II,   PLATE  8 


Tctrabelodon  willistoiii.  a,  mandible  showing  slightly  decurved  sym- 
physis;  deep  groove,  and  two  strong  tusks;  molars  2,  3,  4;  strong  ascend- 
ing rami ;  relatively  high  condyles  and  coronoids,  and  a  pronounced  sig- 
moid  notch,  b,  top  view,  c,  bottom  view. 


MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  183 

Dutch  Creek,  large  banks  of  Pierre  shale  are  exposed.  The  very 
topmost  layer,  some  50  feet  in  thickness,  is  a  bright  ochre-yellow 
color,  instead  of  the  customary  dull,  slate  color.  There  are 
certain  thin,  flinty,  nodular  bands,  traces  of  which  are  found  as 
far  as  Sioux  County.  This  bed  has  been  traced  to  the  west  and  to 
the  north,  well  into  South  Dakota,  especially  around  the  Rosebud 
Agency.  To  the  southwest,  in  Furnas  County,  near  Beaver  City, 
the  ochreous,  flinty,  nodular  layers  are  very  pronounced.  The 
character  of  this  5o-foot  bed  seems  constant,  and  we  made  free  in 
our  field  notes  to  call  it  the  Ainsworth  formation.  Above  the 
Pierre  occurs  the  well  known  Oligocene  bad  lands,  which  in  cer- 
tain exposures  shows  a  thickness  of  about  100  feet.  Immediately 
overlying  this  come  225  feet  of  sandy  beds  belonging  to  the  "  Loup 
Fork."  In  our  field  notes,  we  have  called  this  the  Devil's  Gulch 
stage. 

As  to  the  geological  horizon,  the  faunal  evidence  suggests 
Pliocene  equivalent  to  the  Snake  Creek  beds  of  southern  Sioux 
County.  Possibly  some  Pleistocene  may  be  represented.  Further 
study  will  be  necessary  to  determine  accurately  the  geologic  posi- 
tion of  this  newly  explored  fossil  field.  Faunal  comparisons  show 
this  bed  to  be  much  earlier  than  that  of  Hay  Springs,  and  later 
than  that  of  the  famous  Agate  Springs  Quarries.  It  will  not  be 
far  wrong  to  call  the  Devil's  Gulch  deposits,  Pliocene.  The  upper 
part  may  merge  into  Pleistocene.  Unlike  the  beds  at  Agate 
Springs,  which  are  sufficiently  lithified  to  make  the  chisel  and  pick 
necessary,  the  beds  at  Devil's  Gulch  are  so  loose  and  sandy,  that 
work  is  greatly  facilitated.  Only  occasionally  are  mineralized  or 
concretionary  patches  encountered. 

The  bones,  \vhen  freshly  exhumed,  are  of  a  light  brown  color, 
changing  to  whitish  on  continued  exposure  to  sunlight.  The  bones 
near  the  base  of  the  canyon  seem  to  be  harder  and  more  enduring 
than  those  near  the  top  which  are  soft  and  perishable  to  the  last 
degree,  demanding  skillful  treatment. 

TWO  NEW  MASTODONS  FROM   DEVIL'S   GULCH 

The  discovery  of  two  new  mastodon  skulls,  with  mandibles,  and 
certain  skeletal  parts,  is  of  special  interest,  and  constitutes  the 


184         NEBRASKA  GEOLOGICAL  SURVEY 

main  feature  of  this  collection,  and  of  this  preliminary  report. 
These  skulls  were  found  on  levels  separated  by  75  feet  of  sedi- 
ment, apparently  aqueous  in  origin.  Just  half  way  down  the 
canyon,  at  a  point  named  Quarry  No.  2,  were  found  the  skull, 
mandible,  ribs,  tusk,  and  a  cervical  vertebra  of  a  species  of  young 
"  Tetrabelodon,"  somewhat  similar  to  Trilophodon  productus. 
Seventy-five  feet  higher  than  this  at  Quarry  No.  i,  near  the  rim 
of  the  canyon,  was  found  a  much  larger,  different  mastodon,  with 
skull,  tusks,  mandible,  ribs,  and  pelvis.  We  have  named  these, 
respectively,  Tetrabelodon  willistoni,  and  Eubelodon  morrilli. 

TETRABELODON    WILLISTONI,    sp.    nOV. 

This  species,  consisting  of  a  nearly  perfect  skull  with  mandible, 
one  cervical  vertebra  and  numerous  ribs,  was  found  in  Quarry  No. 
2,  about  115  feet  below  the  general  level,  75  feet  below,  and 
about  300  feet  distant  from  Quarry  No.  i.  This  species  is  named 
for  Dr.  S.  W.  Williston.  The  skull  lacks  parts  of  the  zygoma,  one 
exoccipital,  part  of  the  other,  and  the  basioccipital.  The  man- 
dible is  without  blemish.  The  skull  is  narrow,  and  with  inferior 
dome.  The  occiput,  though  slightly  convex,  is  noticeably  flat,  and 
is  furrowed  but  little  along  the  median  line.  There  is  a  well- 
marked,  though  broad,  occipital  crest.  This  is  very  unlike  the 
occiput  in  Elephas,  which  is  noticeably  convex.  The  exoccipitals 
and  parietals  of  Elephas  round  gently  and  without  crest.  The  pit 
is  so  deep  that  it  extends  well  to  the  inner  cranial  wall.  The 
posterior  nares  are  very  narrow,  and  long  postero-anteriorly.  The 
anterior  nares  are  widely  expanded  with  thick  borders.  The  basi- 
cranial  bones  are  deflected  only  about  10  degrees  from  the  palatine 
plane. 

During  the  growth  of  a  proboscidean,  the  size  of  the  brain  from 
youth  to  maturity  does  not  change  much.  Furthermore,  in  the 
case  of  the  young  of  Elephas,  the  proportion  of  the  cranium  to 
the  brain  is  quite  normal.  But  in  the  case  of  adults,  the  skulls 
are  abnormally  inflated  by  air  cells,  and  this  greatly  emphasizes  the 
disparity  between  the  relatively  small  brain  cavity  and  the  im- 
mense skull.  Though  not  an  adult,  the  air  cells  in  the  skull  of 
Tetrabelodon  willistoni  are  small,  and  the  inflation  moderate.  It 


NEBRASKA   GEOLOGICAL    SURVEY 


VOLUME  4,  PART  II,  PLATE   10 


Eubelodon  morrilli.  a,  mandible,  side  view,  showing  low,  ascending 
rami,  low  condyles  and  coronoids.  Length  43  inches  (1,092  mm.)-  b,  top 
view.  Sixth  molar  8  X  31/  inches  (203  X  89  mm.).  Symphysial  prolonga- 
tion i$l/2  inches  (393  mm.),  c,  bottom  view. 


t 


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>  S 
Ij 

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MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  185 

seems  intermediate  between  the  more  typical  ancestral  forms  and 
the  later  extreme  forms. 

In  all,  some  5  or  6  tusks  of  this  species  were  found.  They 
average  about  3  feet  (915  mm.)  in  length,  and  about  3  inches  (77 
mm.)  in  greatest  diameter.  The  upper  tusks  curve  downward  and 
diverge  at  the  tips,  and  on  the  outer  side  is  a  relatively  broad, 
flat,  enamel  band,  resting  upon  the  dentine  and  presenting  distinct 
edges.  Each  and  every  tusk  from  this  level  shows  a  similar 
enamel  band.  In  the  case  of  one  or  two  tusks,  the  band  has 
become  almost  vestigial,  and  represents  an  interesting  transitory 
stage.  In  one  example,  the  enamel  band  is  about  an  inch  broad 
near  the  tips.  It  rests  upon,  and  well  above,  the  dentine,  and 
presents  distinct  edges.  It  narrows  posteriorly  to  a  fourth  of  an 
inch,  and  its  edges  become  imbedded  in  the  dentine  of  the  tusk. 
Near  the  alveolus,  it  sinks  somewhat  into  the  dentine. 

The  teeth  are  trilophodont.  Those  of  the  upper  jaw  are  four 
in  number,  of  the  lower,  three.  All  of  the  "  Tetrabelodon  "  teeth 
found  on  this  level  seem  to  be  small.  In  the  upper  molars,  the 
outer  tubercles  are  long  and  conical,  with  light  cingulum,  and  with 
no  secondary  cones  to  fill  the  valleys.  On  the  inner  side,  how- 
ever, the  tubercles  are  crowded  with  secondary  cones,  the  valleys 
obstructed,  and  the  cingulum  strong  and  serrated  by  conelets. 

The  mandible  is  in  a  state  of  perfect  preservation.  Its  length 
is  30  inches  (762  mm.)  and  the  extreme  width  across  the  con- 
dyles  is  14^-2  inches  (368  mm.).  It  is  but  slightly  decurved,  and 
has  a  deep  lingual  groove  with  sharp  edges.  The  mandibular 
border  rounds  into  the  ascending  ramus  without  angle.  The 
ascending  ramus  is  strong  and  relatively  high.  The  condyle  has 
a  distinct  neck,  and  stands  4  inches  (102  mm.)  above  the  grinding 
surface  of  the  molars.  The  sigmoid  notch  is  deep,  and  the  coro- 
noid  high  and  prominent.  It  resembles  the  typical  coronoid  more 
closely  than  does  any  proboscidean  with  \vhich  the  writer  is 
familiar.  The  symphysial  prolongation  is  9  inches  (230  mm.). 
Two  strong  mandibular  tusks  project  4  inches  (102  mm.)  from 
the  jaw,  and  are  i-Hs  inches  (42  mm.)  through.  They  are  worn 
obliquely  at  the  tips,  as  shown  in  the  accompanying  cuts.  The 


186         NEBRASKA  GEOLOGICAL  SURVEY 

upper  tusks  had  dropped  out,  but  the  tip  of  one,  found  in  close 
proximity,  undoubtedly  belongs  to  this  skull.  Numerous  other 
tusks  were  found  on  this  level,  and  all  show  pronounced  enamel 
bands.  This  early  proboscidean  is  neither  as  low-browed,  nor  as 
long-jawed  as  one  might  expect. 

The  widely  expanded  anterior  nares,  the  retreating  and  thick- 
ened nasals,  and  the  breadth  of  surfaces  for  attachment  of  muscles, 
suggests  the  probability  of  a  fairly  well-developed,  though  not 
large,  proboscis.  But  the  tusks  were  light,  and  the  combined  load 
imposed  upon  the  neck  muscles  did  not  demand  great  expanse  of 
skull  surface. 

EUBELODON    MORRILLI,  gen.   et  Sp.  nOV.* 

Quarry  No.  I  is  75  feet  higher  up  the  canyon  wall,  and  about 
35  feet  below  the  general  level  of  the  surface,  perhaps  100  yards 
to  the  southeast  of  Quarry  No.  2.  From  this  point,  another 
proboscidean  skull  and  mandible,  complete  pelvis,  ribs,  and  stray 
limb  bones  were  secured.  We  have  named  this  specimen  Eube- 
lodon  morrilli,  in  honor  of  Honorable  Charles  H.  Merrill,  a  former 
President  of  the  Board  of  Regents,  and  for  many  years  a  patron 
of  the  Department.  This  individual  is  larger  in  size  than  the 
first  mentioned,  and  has  marked  structural  differences.  The 
mandible  is  destitute  of  tusks.  In  some  respects,  Eitbelodon  seems 
to  be  a  more  primitive  form  than  Tetrabelodon  willistoni.  It  is 
a  large,  exceptionally  long-jawed,  low-browed  proboscidean.  The 
mandible  is  fully  43  inches  (1,902  mm.)  long,  and  20  inches  (509 
mm.)  across  the  condyles,  and  has  but  one  large  tooth  in  each 
rainus.  The  symphysial  prolongation  is  15^  inches  (393  mm.). 
The  lingual  groove  is  shallow,  with  rounded  edges.  The  skull, 
as  far  as  it  has  been  worked  out  is  rather  flat  and  long. 

The  two  tusks,  found  in  exact  position,  are  finely  preserved. 
They  curve  downward,  slightly  outward,  and  are  without  enamel 
bands.  The  tusks  are  worn  to  sharp,  chisel-like  tips.  A  section 
of  the  tusk  near  the  alveolus  is  an  inverted  ovoid  4^/2  inches  (115 
mm.)  in  vertical  diameter,  and  3^  inches  (89  mm.)  in  horizontal 
diameter,  with  a  pulp  cavity  2^  (70  mm.)  X  i$4  inches  (45  mm.). 

*  The  proposed  generic  name,  Eubelodon,  signifying  well-tusked,  eu- 
phonically  implies  relationship  to  Tetrabelodon  and  Dibelodon. 


NEBRASKA    GEOLOGICAL    SURVEY 


VOLUME  4,  PART   II,   PLATE   13 


Stray     Mastodon     Bones     from     Devil's 
Gulch. 
Eubelodon  morrilli,  a,  b,  c,  d  and  e. 

a,  left  femur  from  above.     X  1A- 

b,  same,  back  view.     X  JA-    Across  head 
and  tuberosity  14  inches   (355  mm.). 

c,  patella. 

d,  right  tibia  and  fibula  united.     Appar- 


X 


Tibia 


ently     nor     pathological. 
inches    (560  mm.)    long. 

e,  left  humerus,   front  view.     X    ?• 

Tetrabelodon  willistoni,  f,  g  and  h. 

f  and  g,  front  and  back  view  of  left 
humerus.  X  T».  Total  length  25  inches 
(635  mm.). 

/!,  five  tusks  showing  varying  widths  of 
enamel  bands. 


MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  187 

The  mandible  of  Eubelodon  morrilli  constitutes  a  striking  char- 
acter. It  is  massive,  straight,  and  of  great  length,  with  low 
ascending  rami.  In  life  the  tusks  projected  scarcely  more  than  a 
foot  and  a  half  beyond  the  jaw  and  lip.  There  are  no  inferior 
tusks.  The  symphysial  prolongation  is  15^2  inches  393  mm.) 
and  is  not  decurved.  The  mandible  is  massive  up  to  the  sym- 
physis,  where  it  begins  to  contract  somewhat,  then  tapers  rapidly 
to  the  tip.  Two  grooves,  one  to  the  right,  and  one  to  the  left, 
parallel  the  lingual  groove,  noticeably  reducing  the  bulk  of  the 
symphysial  portion.  Perhaps  this  is  but  prophetic  that  the  sym- 
physial portion  is  destined  to  become  vestigial  as  in  Elephas. 

In  Eubelodon  morrilli,  the  end  of  the  long,  straight,  massive 
tapering  mandible  comes  well  towards  the  tip  of  the  tusks,  thus 
making  an  interesting,  if  not  grotesque,  facial  portion  to  the 
skull.  It  is  an  unmastodon-like  mastodon.  The  teeth  are  reduced 
to  one  in  each  jaw,  and  they  measure  about  3^/2  inches  (89  mm.) 
by  8  inches  (203  mm.).  These  teeth  have  four  deeply  worn 
ridges,  showing  inner  and  outer  trefoiled  cones,  and  a  small  fifth 
ridge  or  heel.  Alveolar  impressions  in  the  maxillae  show  where  a 
preceding  tooth  has  been  crowded  out  by  a  horizontal  successor. 
The  ascending  rami  are  low,  being  at  most  but  3  inches  (77  mm.) 
above  the  grinding  surface  of  the  molars.  They  are  capped  by 
nearly  circular  condyles  of  low  convexity,  and  unlike  Elephas  are 
without  necks.  Contrast  with  this  Elephas  imperator,  in  which 
the  ascending  rami  are  about  n  inches  (280  mm.)  above  the 
grinding  surface,  and  that  of  Elephas  indicus,  which  are  about 
9  inches  (230  mm.). 

The  coronoids  are  on  a  level  with  the  condyles,  and,  though 
somewhat  compressed,  are  thick  and  strong  compared  with  any 
fossil  or  living  elephant.  The  sigmoid  notch  is  very  shallow.  The 
inferior  mandibular  border,  which  is  very  broad  and  round  at  the 
molars,  narrows  and  swings  by  an  easy  curve  into  the  ascending 
ramus. 

The  tusks  of  Eubelodon  morrilli  are  relatively  large,  but  short, 
distinctly  wedge-shaped  at  the  tips,  and  without  enamel  bands. 
Starting  at  the  skull,  where  the  maxillae  are  just  I  foot  (305  mm.) 
across  from  outside  to  outside,  the  tusks  diverge  until  they  are  3 


188         NEBRASKA  GEOLOGICAL  SURVEY 

feet  (915  mm.)  apart  at  the  tips,  and  curve  downward  slightly. 
Each  tusk  is  4  feet  (1,220  mm.)  long.  One  foot  of  the  tusk  is 
firmly  imbedded  in  the  jaw,  and  an  additional  6  inches  is  partly 
sheathed  and  buttressed  by  the  maxillae.  Since  the  tusks  are 
sheathed  by  the  maxillae  in  the  typical  Proboscidea,  they  have  been 
considered  by  some  as  morphologically  canine  teeth.  The  skulls 
of  young  elephants  show  that  the  tusks  are  erupted  from  the  pre- 
maxillae  and  are  incisors. 

Incident  to  growrth  from  persistent  pulps,  the  young  incisors 
naturally  outgrow  the  limits  of  the  premaxillae,  and  invade  the 
maxillae.  They  are  incisors  grown  indefinitely  large.  In  most 
Tetrabelodons,  there  is  a  conspicuous  bifurcation  of  the  maxillary 
sheath,  but  especially  so  in  Eubelodon  morrilli.  Beyond  the  tips 
of  the  maxillae,  the  tusks  project  30^/2  inches  (776  mm.). 

The  skull  is  still  in  the  hands  of  preparators,  and  has  not  yet 
been  fully  worked  out  or  turned  over,  to  show  the  anterior  narial 
apertures.  From  observation  in  the  quarry,  it  seems  that  the 
surface  for  the  attachment  of  the  muscles  of  the  proboscis  is 
restricted  in  area.  Undoubtedly  the  proboscis,  that  most  distinc- 
tive badge  of  the  group,  was  only  partly  developed,  and  was  short. 

The  posterior  narial  aperture  is  large,  nearly  circular,  and 
with  vertical  walls.  Its  antero-posterior  diameter  is  4^/2  inches 
(115  mm.).  The  transverse  diameter  is  3^2  inches  (90  mm.). 
From  its  anterior  border  to  the  tips  of  the  maxillae  is  24  inches 
(610  mm.).  The  basicranial  elements,  and  the  palate  lie  in  a 
plane  perforated  by  the  postnarial  aperture,  while  in  Elephas 
these  same  parts  are  at  right  angles. 

That  the  cancellous  portions  of  the  bone  of  the  brain  box  lack 
the  extreme  inflation  of  air  cells  common  in  Elephas  is  quite 
apparent,  and  is  readily  accounted  for.  Though  the  head  was  very 
large,  larger  than  an  ordinary  elephant,  the  tusks  and  trunk  were 
not  ponderous,  and  did  not  demand  such  an  abnormal  surface  area 
for  the  attachment  of  muscles. 

The  pelvis,  including  sacrum  and  sacral  spine,  is  perfectly 
preserved,  and  indicates  an  animal  of  large  size.  The  acetabulum 
measures  6l/2  inches  (165  mm.)  in  diameter.  The  neural  arch 
measures  il/>  inches  (38  mm.)  The  pelvic  aperture  is  16  inches 


MAMMALIAN  FOSSILS  FROM  DEVIL'S  GULCH  189 

(407  mm.)  transversely,  by  14  inches  (356  mm.)  vertically.  The 
thyroid  foramen  is  7^  X  4>^  inches  (192X115  mm.).  The 
extreme  width  across  the  ilia  is  56  inches (1424  mm.). 

PARTIAL  FAUNAL  LIST,  DEVIL'S  GULCH  BEDS 

Turtle 

1.  Testudo  orthop\gia 

2.  Testudo,  undetermined. 
Canids 

3.  Aelurodon 

4.  Tephrocyon 

5.  Cynarctus,  sp.  nov. 

6.  Cyon 

7.  Temnocyont 
Mustelids 

8.  Mustelid,  undetermined 
Felids 

9.  Machaerodus,  sp.  nov. 
Camels 

10.  O.vydactylus 

11.  Alticamelus 

12.  Procamelus 

13.  Pliauchenia 

14.  Camel,  undetermined 
Oreodonts 

15.  Metoreodon 
Merycodonts 

16.  Merycodus  necatus 
Rhinoceros 

17.  Teleoceras 

1 8.  Rhinoceros,  undetermined 
Equids 

19.  Parahippus 

20.  Hypohippus 

21.  Mery chip pus 

22.  Protohippus 


190         NEBRASKA  GEOLOGICAL  SURVEY 

23.  Pliohippus 

24.  Hipparion 
Proboscideans 

25.  Tetrabelodon  zvillistoni,  sp.  nov. 

26.  Mastodon  euhypodon? 

27.  Mastodon,  undetermined 

28.  Mastodon  morrilli,  sp.  nov. 

THE  UNIVERSITY  OF  NEBRASKA. 
December,  1913 


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